Field studies – technology & significance for coastal engineering projects

Ocean environment is generally dynamic in nature with rise and fall of tides, density driven current and surface waves. The interface where the ocean meets the lands mass is broadly termed as the coast and the physical transition between the land and sea is the shoreline. The shoreline is subjected to continuous changes with wave actions and which in turn causing the littoral drift. [1] The coast is influenced with various anthropogenic activities and development project like ports & harbour development, construction of jetties, laying of intake and outfall pipeline for desalination plants & power plants etc. Any unplanned execution of work in this dynamic environment will leads to shoreline erosion loss of available land. Unlike conducting terrain survey on land, conducting hydrographical survey or oceanographic investigations need detailed understanding of the environment with associated sea state. Collection of oceanographic data plays a vital role in design and development of any infrastructural project along the coast. It has often been observed that design based on insufficient data result in infrastructure failure which often leads to difficulties during the construction and operation stages of the infrastructure. Typical examples are damage to groyne structures due to monsoon waves, siltation of ports & harbours leading to expensive dredging. Hence, the importance of field studies is very crucial in capturing the inputs and data required for proper design. One must thoroughly study the dynamic of waves, tides, currents, seabed stratification, seafloor classification and more importantly the nearshore bathymetry for understanding the dynamic coastal environment. It can be achieved by adopting sophisticated instruments like echosounders for measuring depth, acoustic based devices like seismic for seabed studies and sidescan to capture seafloor image operating with certain frequencies, tide recorder and current meter to record the time series variations of tides and currents in any coastal region [2]. Very few organizations in India have the capability to plan and execute such marine related studies. Among them the leading institutions to name a few are Ocean Engineering Department of IIT Madras, CWPRS-Pune, NIO-Goa, NIOT and NCCR-Chennai. Organizations like Indomer who have been in this field for the past 23 years have matched such infrastructure and have been able to navigate the requirements of conducting studies in the east and west coast of India. Coastal infrastructures projects are also subjected to catastrophic events like tsunami, cyclone, and storm surges etc. It is imperative that such effects can be predicted through modelling studies. The data collected from field studies are in turn used to calibrate numerical model and further scenarios are then simulated using established numerical modelling tools to understand these events. It is now possible to simulate conditions for tide, current, sediment transport, oil spill, shoreline changes etc. through modelling suites such as MIKE21, Delft3D, SWAN etc. [3]. This approach of conducting field studies supplemented with mathematical modelling will help design coastal infrastructure in a safe efficient and cost-effective manner. This paper describes in detail the various field surveys, field equipments, methodology adopted, and typical mathematical modelling studies carried out for coastal infrastructure project with Indian perspective in mind.